1. Field of the Invention
The present invention relates in general to plugs and a method of installing and removing a plug device, and relates in particular to removable plug device which forms a seal when fitted in an opening.
2. Description of the Related Art
A rim of an automobile wheel is provided with an opening for attaching an air valve. For use in tubeless tires, this type of rim must be tested for leaks by plugging the opening with a plugging device, as a part of the process of manufacturing the rim.
In performing such a test, a plug device such as the one shown in FIGS. 9A and 9B, for example, is used. The plug device 30 is made of a solid cylindrical plug body 31 having a tapered surface 31A at its leading tip end and a seal section 31B formed around the outer periphery, and a flange section 32 at the tail end of the plug body 31, which is at the opposite end to the direction of insertion of the plug device 30. The plug device 30 is made of a rubber material, and when the plug device 30 is inserted into the opening section 33 of a workpiece W, the sealing action is provided by the sealing section 31B fitting tightly the opening section 31.
To insert the plug device 30 into the opening section 33, the tapered surface 31A of the plug body 31 is first manually inserted into the opening section 33, and using a rod-shaped jig 34 abutting against the flange section 32, the plug device 30 is pushed in the direction of the arrow shown in the drawing into the hole section 33. When the plug device 30 is to be removed, the flange section 32 is clamped with a suitable tool and is pulled in the opposite direction to the insertion direction.
However, the conventional plug device such as the plug device 30 shows a tendency to form a local bulge region 31C in the seal section 31B of the plug body 31, as illustrated in FIG. 9A. This is because the material is made of rubber to effect sealing and because the plug device 30 is formed as a solid member, and also because the outer diameter of the plug body is slightly larger than the opening section 33 so as to provide a pressure fit. The result is that because of the generation of the bulge region 31C, it is difficult to insert the plug device 30 to the full depth so that the flange section 32 fits flush with the workpiece W, as illustrated in FIG. 9B.
Furthermore, as illustrated in FIG. 9B, when the plug device 30 is fully inserted into the opening section 33, the diameter of the solid flange section 32 is larger than the diameter of the opening section, so the plug device 30 cannot be removed by further forcing the plug device 30 in the insertion direction. Therefore, removal of the conventional plug device is always carried out by grasping the flange section 32 and pulling out the plug device 30 in the direction opposite to the insertion direction. However, because the plug device 30 is elastic and the outer periphery of the flange section expands to present a round profile as illustrated in FIG. 9B, it is not always easy to grip the flange section 32 sufficiently tightly for quick removal.
The process of pulling out the plug device 30 is far more laborious compared with the process of insertion of the plug device 30, and coupled with the difficulty of installation, the problem has been the expectation that a simple and quick method of installation/removal does not exist. Additionally, if the flange section 32 is damaged during the gripping step, the plug device 30 can no longer be reused, and it presented another problem that the plug device is uneconomic.